Ant Trail Pheremone

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Project Topic:

Refining of Ores by Electrowinning (Reduction of Oxides)

Chemistry Concept:

Most ores are either oxides or sulfides. Sulfides can be easily converted into oxides by heating in the presence of oxygen, so our lab will focus on the oxides. To recover the pure metal, the compound has to transfer its oxygen to another atom or atoms. There are three main methods of doing so: pyrometallurgy, which uses heat to break the metal-oxygen bond, electrometallurgy, which uses electric current to electroplate a pure metal cathode, and hydrometallurgy, which uses aqueous chemistry to reduce the metal. The metal used will be copper. We will use pyrometallurgy to create a solid, somewhat pure sample, which will be further refined with electrometallurgy.

Hypothesis:

A high voltage will improve purity. Pyrometallurgic methods of purification will result in less pure copper than electrometallurgy.
.

Journal Articles:

Pyrometallurgy: http://tinyurl.com/7jdu7xo
Electrometallurgy: http://tinyurl.com/893nfph

Lab Procedure:

All:
Mass out ~10 g of copper oxide, record

Pyro:
  1. Acquire two sections of glass tubing each about ~9-10 inches in length. Using a bunsen burner bend one into a L shape and one into a Z shape.
  2. Attach both sections of tubing to a double holed stopper. The Z shaped tube will be a gas flare; make sure it is as far away as possible from the L shaped gas input.
  3. Place copper oxide powder in test tube (mass test tube) and and secure tube to ring stand horizontally. Place stopper with tubing into test tube and attach L shaped glass tube to methane input (using length or rubber tubing.) Before moving to step 4, make sure copper oxide is spread along the wall of the test tube not clumped in the end.
  4. Open the valve to allow methane to flow into the test tube and light gas flare at end of Z shaped tube.
  5. Use a Bunsen burner to heat copper oxide until it changes color (from black to light pink.)
  6. Once all the copper oxide has visibly reacted, turn off the Bunsen burner. DO NOT TURN OFF THE GAS FLOWING THROUGH THE TEST TUBE! THIS WILL CAUSE THE COPPER TO OXIDIZE.
  7. Wait until the test tube and its contents have cooled to room temperature, then stop the flow of gas through the test tube and remove stopper. DO NOT OPEN THE TEST TUBE NEAR AN OPEN FLAME, ALLOW EXCESS METHANE TO DISPERSE SAFELY.
  8. Re mass the test tube and record the new mass. Calculate percent yield.

Electro:
  1. Fill a 500mL flask with 1.0 M sulfuric acid
  2. Mass out 20 g of copper sulfate, and add to the beaker
  3. Acquire two sections of copper wire, (twist into a spiral pattern to maximize surface area in sulfuric acid solution.) Mass the pure copper leads (anode and cathode), record.
  4. Pour 10g of copper (II) oxide into flask.
  5. Thread anode and cathode through stopper, attach to current source, and place stopper in beaker. MAKE SURE ANODE AND CATHODE ARE NOT TOUCHING.
  6. Set the current source to .1V for trial one, 3V for trial two. In both cases allow the solution to sit, with current on, for 5 minutes.
  7. When the anode is consumed, remove the anode and cathode, mass both and record
  8. Calculate percent yield.

Apparatus and Chemicals Needed:

Substrates:
Copper(II) oxide

Pyro:
  1. Bunsen Burner
  2. Ring Stand
  3. Clamp
  4. Test tube
  5. Glass tubing
  6. Rubber tubing
  7. 2xMethane sources
  8. Double Hole Stopper


Electro:
  1. Copper sulfate
  2. Copper cathode/anode
  3. 1.0M Sulfuric acid
  4. Current source
  5. Double Hole Stopper

Other:
Digital scale, plexiglass shield

Safety Information:

Do not inhale, ingest or touch the copper (II) oxide or copper sulfate.
Be wary of hot glassware and fire hazard when using methane to reduce copper (II) oxide. Place plexiglass shield between observer and apparatus.
Do not inhale, ingest or touch sulfuric acid. Handle with care and dispose of properly.
Use fume hood for electrolysis.
Do not touch electric leads during electrolysis.

Material Safety Data Sheets:
Copper(II) oxide
Copper(II) sulfate
Methane

Data Collected:

Pyro
 Mass
Empty test tube
 18.42 g
Copper oxide
 2.5 g
Test Tube and copper
 20.57 g
copper
 2.15 g
Electro (0.5 V)
 Mass
Empty beaker
 125.57 g
Anode before
 0.21 g
Cathode before
 0.30 g
Copper sulfate
 10.00 g
Beaker and sulfuric acid
 331.03 g
Beaker and sulfuric acid and copper sulfate
 340.94 g
Anode after
 0.21 g
Cathode after
 0.25 g
Beaker and contents after
 343.46 g
Electro (3 V)
 Mass
Empty beaker
 125.57 g
Anode before
 0.70 g
Cathode before
 0.58 g
Copper sulfate
 10.00 g
Beaker and sulfuric acid
 347.05 g
Beaker and sulfuric acid and copper sulfate
 356.75 g
Anode after
 0.88 g
Cathode after
 0.54 g
Beaker and contents after
 343.14 g

Lab Revisited:


We revisited the electroplating portion of the lab and conducted 5 additional trials using various voltages. Our additional trials supported the conclusion that copper was successfully plated out of solution. The 5 additional trials also refined our methodology for doing so.

Project Topic:

Refining of Ores by Electrowinning (Reduction of Oxides)

Chemistry Concept:

Most ores are either oxides or sulfides. Sulfides can be easily converted into oxides by heating in the presence of oxygen, so our lab will focus on the oxides. To recover the pure metal, the compound has to transfer its oxygen to another atom or atoms. There are three main methods of doing so: pyrometallurgy, which uses heat to break the metal-oxygen bond, electrometallurgy, which uses electric current to electroplate a pure metal cathode, and hydrometallurgy, which uses aqueous chemistry to reduce the metal. The metal used will be copper. We will use pyrometallurgy to create a solid, somewhat pure sample, which will be further refined with electrometallurgy. We will investigate the relationship between current and rate of plating.

Hypothesis:

A high current will be directly proportional to rapid plating. Pyrometallurgic methods of purification will result in less pure copper than electrometallurgy.
.

Journal Articles:

Pyrometallurgy: http://tinyurl.com/7jdu7xo
Electrometallurgy: http://tinyurl.com/893nfph

Lab Procedure:


Pyro:
  1. Mass out ~10 g of copper oxide, record
  2. Acquire two sections of glass tubing each about ~9-10 inches in length. Using a bunsen burner bend one into a L shape and one into a Z shape.
  3. Attach both sections of tubing to a double holed stopper. The Z shaped tube will be a gas flare; make sure it is as far away as possible from the L shaped gas input.
  4. Place copper oxide powder in test tube (mass test tube) and and secure tube to ring stand horizontally. Place stopper with tubing into test tube and attach L shaped glass tube to methane input (using length or rubber tubing.) Before moving to step 4, make sure copper oxide is spread along the wall of the test tube not clumped in the end.
  5. Open the valve to allow methane to flow into the test tube and light gas flare at end of Z shaped tube.
  6. Use a Bunsen burner to heat copper oxide until it changes color (from black to light pink.)
  7. Once all the copper oxide has visibly reacted, turn off the Bunsen burner. DO NOT TURN OFF THE GAS FLOWING THROUGH THE TEST TUBE! THIS WILL CAUSE THE COPPER TO OXIDIZE.
  8. Wait until the test tube and its contents have cooled to room temperature, then stop the flow of gas through the test tube and remove stopper. DO NOT OPEN THE TEST TUBE NEAR AN OPEN FLAME, ALLOW EXCESS METHANE TO DISPERSE SAFELY.
  9. Re mass the test tube and record the new mass. Calculate percent yield.

Electro:
  1. Fill a 500mL flask with 100 mL 1.0 M sulfuric acid
  2. Mass out 4.0 g of copper sulfate, and add to the beaker
  3. Acquire a section of copper wire, (twist into a spiral pattern to maximize surface area in sulfuric acid solution.) Mass and record
  4. Create anode
    1. For graphite, bind together 10 sticks of pencil lead with a copper wire. Mass and record.
    2. For direct contact, clamp a nickel coin in a pair of tweezers, and wrap wire around the middle to keep the tweezers closed.
  5. If using a graphite anode, mass the nickel.
  6. Attach the copper wire to the black wire (negative), and the anode to the red (positive) terminal of the current source, and place stopper in beaker. MAKE SURE ANODE AND CATHODE ARE NOT TOUCHING. For a graphite anode, place the nickel underneath the anode.
  7. Set the current source to a predetermined voltage. In both cases allow the solution to sit, with current on, for 45 minutes.
  8. Every 5 minutes, and at the start of the experiment, record both voltage and current from the power source.
  9. After 45 minutes, remove electrodes, and mass anode, cathode, and nickel.

Apparatus and Chemicals Needed:

Substrates:
Copper(II) oxide

Pyro:
  1. Bunsen Burner
  2. Ring Stand
  3. Clamp
  4. Test tube
  5. Glass tubing
  6. Rubber tubing
  7. 2xMethane sources
  8. Double Hole Stopper


Electro:
  1. Copper sulfate
  2. Copper wire
  3. Tweezers
  4. 1.0 M Sulfuric acid
  5. Current source
  6. U.S. nickel (pre-1945)

Other:
Digital scale, plexiglass shield

Safety Information:

Do not inhale, ingest or touch the copper (II) oxide or copper sulfate.
Be wary of hot glassware and fire hazard when using methane to reduce copper (II) oxide. Place plexiglass shield between observer and apparatus.
Do not inhale, ingest or touch sulfuric acid. Handle with care and dispose of properly.
Use fume hood for electrolysis.
Do not touch electric leads during electrolysis.

Material Safety Data Sheets:
Copper(II) oxide
Copper(II) sulfate
Methane

Data Collected:

Table 1: Masses of Compounds During Smelting
 Mass
Empty test tube
 18.42 g
Copper oxide
 2.5 g
Test Tube and copper
 20.57 g

Table 2: Initial conditions for Electroplating

Trial 1
 Trial 2
 Trial 3
 Control 1
 Control 2
Anode mass
 0.255 g
 0.558 g
 0.726 g
 23.919 g
 24.017 g
Cathode mass
 2.116 g
 2.261 g
 1.854 g
 1.879 g
 7.191 g
Nickel (coin) mass
 5.058 g
 5.020 g
 4.939 g
 N / A
 N / A
Copper sulfate mass
 3.996 g
 3.997 g
 4.000 g
 4.000 g
 3.999 g
Sulfuric acid volume
 102.0 mL
 100.0 mL
 100.2 mL
 96.0 mL
 100.0 mL

Table 3: Voltage and Current Measurements for Electroplating

Trial 1
 Trial 2
 Trial 3
 Control 1
 Control 2
Time = 0 min
 2.9 V
 0.35 A
 6.0 V
 2.39 A
 4.0 V
 0.89 A
 5.2 V
 3.03 A
 4.5 V
 3.06 A
5
 2.9 V
 0.30 A
 6.0 V
 2.76 A
 4.0 V
 1.09 A
 5.4 V
 3.03 A
 4.6 V
 3.05 A
10
 2.8 V
 0.34 A
 5.9 V
 2.83 A
 3.9 V
 1.10 A
 4.0 V
 3.02 A
 4.4 V
 3.05 A
15
 2.8 V
 0.41 A
 6.0 V
 0.60 A
 4.0 V
 1.09 A
 4.6 V
 3.02 A
 4.0 V
 3.05 A
20
 2.9 V
 0.47 A
 6.0 V
 0.22 A
 4.0 V
 1.85 A
 4.5 V
 3.02 A
 4.5 V
 3.05 A
25
 2.8 V
 0.51 A
 6.0 V
 0.18 A
 4.0 V
 1.31 A
 4.4 V
 3.02 A
 4.4 V
 3.05 A
30
 2.8 V
 0.53 A
 6.0 V
 0.07 A
 4.0 V
 1.32 A
 4.4 V
 3.02 A
 4.5 V
 3.04 A
35
 2.8 V
 0.55 A
 6.0 V
 0.17 A
 4.0 V
 1.21 A
 4.3 V
 3.02 A
 4.5 V
 3.04 A
40
 2.9 V
 0.55 A
 6.0 V
 0.12 A
 4.0 V
 1.00 A
 4.3 V
 3.01 A
 4.4 V
 3.04 A
45
 2.8 V
 0.54 A
 6.0 V
 0.10 A
 4.0 V
 0.61 A
 4.4V
 3.01 A
 4.4 V
 3.04 A

Table 4: Final conditions for Electroplating

Trial 1
 Trial 2
 Trial 3
 Control 1
 Control 2
Anode mass
 0.208 g
 5.016 g
 4.776 g
 21.199 g
 21.742 g
Cathode mass
 3.106 g
 2.388 g
 3.268 g
 8.292 g
 11.367 g
Nickel (coin) mass
 5.009 g
 0.391 g
 0.554 g
 N / A
 N / A

Table 5: Mass Changes in Components

Trial 1
 Trial 2
 Trial 3
 Control 1
 Control 2
Change in Cathode
 0.99 g
 0.127 g
 1.414 g
 6.413 g
 4.176 g
Change in Anode
 0.047 g
 4.458 g
 4.05 g
 N / A
 N / A
Change in Nickel
 0.049 g
 4.629 g
 4.385 g
 N / A
 N / A
Change in Anode + Nickel
 0.096 g
 9.087 g
 8.435 g
 2.72 g
 2.275 g

Table 6: Total Charge Transferred
Current to Charge Table
 Trial 1
 Trial 2
 Trial 3
 Control 1
 Control 2
Charge (Columbs)
 1130
 2460
 3220
 8150
 8230
Charge (mol electrons)
 0.0117
 0.255
 0.0334
 0.0845
 0.0852